title: Yeast Upf1 CH domain interacts with Rps26 of the 40S ribosomal subunit.
abstract: The central nonsense-mediated mRNA decay (NMD) regulator, Upf1, selectively targets nonsense-containing mRNAs for rapid degradation. In yeast, Upf1 preferentially associates with mRNAs that are NMD substrates, but the mechanism of its selective retention on these mRNAs has yet to be elucidated. Previously, we demonstrated that Upf1 associates with 40S ribosomal subunits. Here, we define more precisely the nature of this association using conventional and affinity-based purification of ribosomal subunits, and a two-hybrid screen to identify Upf1-interacting ribosomal proteins. Upf1 coimmunoprecipitates specifically with epitope-tagged 40S ribosomal subunits, and Upf1 association with high-salt washed or puromycin-released 40S subunits was found to occur without simultaneous eRF1, eRF3, Upf2, or Upf3 association. Two-hybrid analyses and in vitro binding assays identified a specific interaction between Upf1 and Rps26. Using mutations in domains of UPF1 known to be crucial for its function, we found that Upf1:40S association is modulated by ATP, and Upf1:Rps26 interaction is dependent on the N-terminal Upf1 CH domain. The specific association of Upf1 with the 40S subunit is consistent with the notion that this RNA helicase not only triggers rapid decay of nonsense-containing mRNAs, but may also have an important role in dissociation of the premature termination complex.
authors.affiliation: Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts 01655, USA.
authors.forename: Ei Ei
authors.initials: EE
authors.lastname: Min
authors.forename: Bijoyita
authors.initials: B
authors.lastname: Roy
authors.forename: Nadia
authors.initials: N
authors.lastname: Amrani
authors.forename: Feng
authors.initials: F
authors.lastname: He
authors.forename: Allan
authors.initials: A
authors.lastname: Jacobson
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D018389:Codon, Nonsense; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D059365:Nonsense Mediated mRNA Decay; D054730:Protein Interaction Domains and Motifs; D021122:Protein Subunits; D020365:RNA Helicases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D012331:RNA, Fungal / Q000235:genetics / Q000378:metabolism; D012269:Ribosomal Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D018389:Codon, Nonsense; D021122:Protein Subunits; D012331:RNA, Fungal; C489204:RPS26A protein, S cerevisiae; D012269:Ribosomal Proteins; D029701:Saccharomyces cerevisiae Proteins; D000251:Adenosine Triphosphatases; C074151:NAM7 protein, S cerevisiae; D020365:RNA Helicases
keywords: NMD; RNA helicase; ribosomal proteins